GRAIN INCOMPLETE FILLING 2 regulates grain filling and starch synthesis during rice caryopsis development

Abstract

Rice grain filling determines grain weight, final yield and grain quality. Here, a rice defective grain filling mutant, gif2, was identified. Grains of gif2 showed a slower filling rate and a significant lower final grain weight and yield compared to wild-type. The starch content in gif2 was noticeably decreased and its physicochemical properties were also altered. Moreover, gif2 endosperm cells showed obvious defects in compound granule formation. Positional cloning identified GIF2 to encode an ADP-glucose pyrophosphorylase (AGP) large subunit, AGPL2; consequently, AGP enzyme activity in gif2 endosperms was remarkably decreased. GIF2 is mainly expressed in developing grains and the coded protein localizes in the cytosol. Yeast two hybrid assay showed that GIF2 interacted with AGP small subunits OsAGPS1, OsAGPS2a and OsAGPS2b. Transcript levels for granule-bound starch synthase, starch synthase, starch branching enzyme and starch debranching enzyme were distinctly elevated in gif2 grains. In addition, the level of nucleotide diversity of the GIF2 locus was extremely low in both cultivated and wild rice. All of these results suggest that GIF2 plays important roles in the regulation of grain filling and starch biosynthesis during caryopsis development, and that it has been preserved during selection throughout domestication of modern rice.

Impact of soil salinity on grain yield and aromatic compound in Thai Hom Mali rice cv. Khao Dawk Mali 105

“…On the other hand, the current study showed that the salt treatments affected the individual seed weight which consequently affected the grain yield as indicated by the correlation between grain yield and electrical conductivity and 1,000 seed weight which was reported by Gay et al (2010). This phenomenon has been explained as perhaps being due the limited grain-filling process during grain development (Wei et al, 2017). Grain filling is the process of accumulating starch in rice which is an end product of photosynthesis and which saline soil was found to depress during processing (Chaves et al, 2009).…”

Production of very‐high‐amylose cassava by post‐transcriptional silencing of branching enzyme genes

“…Therefore, the development of cassava varieties having novel starches including waxy (amylose‐free) and high‐amylose starches are important objectives for cassava breeders (Zhang et al 2017). The target genes are mainly involved in starch biosynthesis, such as ADP‐glucose pyrophosphorylase, granule bound starch synthases (GBSS), soluble starch synthases (SSS), starch branching enzyme (SBE or BE), debranching enzyme (DBE), and related kinases (Zeeman et al 2010; Bahaji et al 2014; Wei et al 2017; Cai et al 2018). More specifically, the SSS, BE, and DBE are involved in amylopectin synthesis, and GBSS is the key enzyme for amylose biosynthesis in plants including cassava (Yang et al 2011; Zhao et al 2011; Bull et al 2018).…”

OsPK2 encodes a plastidic pyruvate kinase involved in rice endosperm starch synthesis, compound granule formation and grain filling

“…Mutation of those genes changes the appearance of the endosperm and alters the characteristics of storage starch. For instance, mutations in AGPase subunits create a wrinkled endosperm and significantly reduce the starch content (Akihiro et al, 2005;Lee et al, 2007;Tuncel et al, 2014;Wei et al, 2017). Loss-of-function mutations of the GBSSI gene produce a complete lack of endosperm amylose (Sato et al, 2002;Tian et al, 2009).…”